Search Results (5,045)

This study focuses on optimizing the flow field uniformity within a vertical honeycomb wet electrostatic precipitator (WESP), which is a critical prerequisite for achieving high particulate removal efficiency. For a vertical honeycomb WESP with an air capacity of 25,000 m³/h, the internal flow field is optimized by adjusting the opening ratio and aperture ratio of the airflow equalizing plate, installing additional deflector plates, and adding additional airflow equalizing plates at strategic locations. The optimization reduces the velocity relative standard deviation at the anode inlet section to 0.14. Through 1:1-scale equipment construction and testing, the particle concentration at the outlet is stabilized below 10 mg/Nm³, with an average removal efficiency of 95.88%—a 5.7% improvement over the original model. This study solves the design dependency on empirical guidance for vertical honeycomb WESP in the food industry, providing a green technology paradigm for low-carbon industrial emissions. Full article

Full waveform inversion (FWI) comprehensively utilizes phase and amplitude information of seismic waves to obtain high-resolution subsurface medium parameter models, applicable to both active-source and passive-source seismic data. Passive-source seismic exploration, using natural earthquakes or ambient noise, reduces costs and environmental impact, with growing marine applications in recent years. Its rich low-frequency content makes passive-source FWI (PSFWI) a key research focus. However, PSFWI inversion quality relies heavily on accurate virtual source reconstruction. While multi-dimensional deconvolution (MDD) can handle uneven source distributions, it struggles with irregular receiver sampling. We propose a robust MDD method based on multi-domain stepwise interpolation to improve reconstruction under non-ideal source and sampling conditions. This approach, validated via an adaptive PSFWI strategy, exploits MDD’s insensitivity to source distribution and incorporates normalized correlation objective functions to reduce amplitude errors. Numerical tests on marine and complex scattering models demonstrate stable and accurate velocity inversion, even in challenging acquisition environments. Full article

Methane steam reforming is the most widely adopted hydrogen production technology. To address the challenges associated with the large radial thermal resistance and low mass transfer rates inherent in the tubular packed bed reactors during the MSR process, this study proposes a structural design optimization that integrates annular metal foam gas channels along the inner wall of the reforming tubes. Utilizing multi-physics simulation methods and taking the conventional tubular reactor as a baseline, a comparative analysis was performed on physical parameters that characterize flow behavior, heat transfer, and reaction in the reforming process. The integration of the annular channels induces a radially non-uniform distribution of flow resistance in the tubes. Since the metal foam exhibits lower resistance, the fluid preferentially flows through the annular channels, leading to a diversion effect that enhances both convective heat transfer and mass transfer. The diversion effect redirects the central flow toward the near-wall region, where the higher reactant concentration promotes the reaction. Additionally, the higher thermal conductivity of the metal foam strengthens radial heat transfer, further accelerating the reaction. The effects of operating parameters on performance were also investigated. While a higher inlet velocity tends to hinder the reaction, in tubes integrated with annular channels, it enhances the diversion effect and convective heat transfer. This offsets the adverse impact, maintaining high methane conversion with lower pressure drop and thermal resistance than the conventional tubular reactor does. Full article

Water resource management is critical for sustainable agriculture, especially in regions like Kazakhstan that face significant water scarcity challenges. This paper presents the development of a real-time water-level monitoring system designed to optimize water use in agriculture. The system integrates IoT sensors and cloud technologies, and analyzes data on water levels, temperature, humidity, and other environmental parameters. The architecture comprises a data collection layer with solar-powered sensors, a network layer for data transmission, a storage and integration layer for data management, a data processing layer for analysis and forecasting, and a user interface for visualization and interaction. The system was tested at the Left Bypass Canal in Taraz, Kazakhstan, demonstrating its effectiveness in providing real-time data for informed decision-making. The results indicate that the system significantly improves water use efficiency, reduces non-productive losses, and supports sustainable agricultural practices. Full article

This article focuses on how to further explore the impact of building layout and form on the local wind environment in micro scale ventilation corridors connected to the urban scale. Taking Shijiazhuang as the research area, three typical blocks of complex building forms, including old and new ones, were selected near the built ventilation corridors. CFD numerical simulation and on-site observation experiments were conducted to analyze the impact of different building heights and layouts on the wind environment in each typical block qualitatively and quantitatively. The above can provide a reference and guidance for the construction of secondary and tertiary ventilation corridors and the spatial form design of functional buildings during urban renewal in the stock era. The results show the following: (1) average wind speed, Mean Wind Velocity ratio, and the proportion of the outdoor pedestrian comfort zone are negatively correlated with the building height, but there is a threshold for them to decrease with the increase in the building height. Observation experiments also indicate that in the background of the south wind, the internal and leeward wind environment of new high-rise residential areas is better than that of old low residential areas. (2) Regression analysis was conducted between the simulated average wind speed and the building height, indicating that regulating the average building height to be below 45 m can improve the wind environment as the building height decreases. (3) The enclosed building complex has the smallest impact distance on downstream wind speed compared to point, row, and staggered layouts, but its internal ventilation environment is relatively poor. To ensure the ventilation performance, the upper limit of the building height should be stricter, and it should be controlled within at least 40 m, especially below 30 m. (4) In the process of urban renewal in the future, it is recommended to conduct an overall ventilation efficiency evaluation for different blocks. Compared to others, increasing the height of buildings and leaving more space to increase the inter site ratio/building spacing is more beneficial for the overall ventilation environment. Full article

To constrain Tianchi Volcano basalt petrogenesis, this study focuses on tholeiitic basalts from the CZK06 drill core on the northern slope. Using elemental geochemistry and Mg isotope analyses, we investigate magma evolution, petrogenesis, and mantle source properties. The tholeiitic basalts formed during the Pliocene-Early Pleistocene shield-forming stage, recording three stages of basaltic volcanism (Phases I to III). Classified as sodium-series basalts, they exhibit geochemical affinities with EM1-type OIB. Their δ²⁶Mg values (−0.420‰ to −0.150‰) show a substantially wider range than N-MORB. Their geochemical compositions are primarily controlled by source region characteristics and partial melting degree, with minor additional influences from fractional crystallization and crustal contamination. Fractional crystallization intensity shows a progressive increase from Phase I to III. Integrated with geochemical tracing studies of Changbaishan basalts, we propose that the tholeiitic basalts are derived predominantly from the partial melting of carbonatized pyroxenite, which originated from subducted ancient clay-rich altered oceanic crust. The carbonate melts driving the carbonatization were generated by low-pressure melting of recent oceanic sediments, transported by the deeply subducted carbonate-rich Pacific Plate within the Mantle Transition Zone. The tholeiitic magma formed in the Low-Velocity Zone at depths of 160–180 km beneath the lithospheric mantle. Full article

Background: Recurrent haemarthrosis leads to progressive and degenerative joint damage in patients with haemophilia from an early age. Haemophilic arthropathy is characterised by chronic pain, restricted range of motion, proprioceptive deficits, and structural alterations. The aim of this study was to evaluate the effectiveness of a manual therapy protocol in patients with haemophilic ankle arthropathy. Methods: A randomised, crossover, double-blind clinical trial was conducted. Thirteen patients with haemophilia were allocated to two sequences: A–B (intervention phase followed by placebo control) and B–A (placebo control followed by intervention). The intervention comprised joint mobilisation techniques, high-velocity low-amplitude manipulations, and myofascial release. In the placebo control condition, a simulated protocol was applied, consisting of intermittent contact and light pressure. Both conditions involved three physiotherapy sessions, delivered once weekly over three consecutive weeks. Outcome measures included functional capacity (2-Minute Walk Test), pain intensity (visual analogue scale), range of motion (goniometer), pressure pain threshold (algometer), joint status (Haemophilia Joint Health Score), kinesiophobia (Tampa Scale of Kinesiophobia), and postural stability (pressure platform). Following a four-week washout period, participants crossed over to the alternate condition. Results: No participants experienced ankle haemarthrosis or other adverse events during the intervention, confirming the safety of the protocol. Significant time*sequence interactions (p < 0.05) with high post hoc power (≥0.80) were observed for functional capacity, range of motion, and joint status. A significant sequence effect was also found for most clinical outcomes, with no evidence of a carry-over effect. Conclusions: This manual therapy protocol might be safe for patients with haemophilia. The physiotherapy intervention demonstrated improvements in functionality, range of motion, and joint status in individuals with haemophilic ankle arthropathy. Full article

The swinging sticks pendulum is an intriguing physical system that exemplifies the intersection of Lagrangian mechanics and chaos theory. It consists of a series of slender, interconnected metal rods, each with a counterweighted end that introduces an asymmetrical mass distribution. The rods are arranged to pivot freely about their attachment points, enabling both rotational and translational motion. Unlike a simple pendulum, this system exhibits complex and chaotic behavior due to the interplay between its degrees of freedom. The Lagrangian formalism provides a robust framework for modeling the system’s dynamics, incorporating both rotational and translational components. The equations of motion are derived from the Euler–Lagrange equations and lack closed-form analytical solutions, necessitating the use of numerical methods. In this work, we employ the Bulirsch–Stoer method, a high-accuracy extrapolation technique based on the modified midpoint method, to solve the equations numerically. The system possesses four fixed points, each one associated with a different level of energy. The fixed point with the lowest energy level is a center, around which small perturbations are studied. The other three fixed points are unstable. The maximum energy used for the perturbations is $0.001\%$ larger than the lowest equilibrium energy. When the system’s total energy is low, nonlinear terms in the equations can be neglected, allowing for a linearized treatment based on small-angle approximations. Under these conditions, the pendulum oscillates with small amplitudes around a stable equilibrium point. The resulting motion is analyzed using tools from nonlinear dynamics and Fourier analysis. Several trajectories are generated and examined to reveal frequency interactions and the emergence of complex dynamical behavior. When a small initial perturbation is applied to one rod, its motion is characterized by a single frequency with significantly greater amplitude and angular velocity compared to the second rod. In contrast, the second rod displayed dynamics that involved two frequencies. The present study, to the best of our knowledge, is the first attempt to describe the dynamical behavior of this pendulum. Full article

Long-distance water conveyance systems require controlled filling after initial operation or maintenance. This process is complex and challenging to manage accurately. It involves transient two-phase flow with rapid velocity and pressure changes, which can risk pipeline damage. Studying the filling process is thus essential to ensure the safe and efficient operation of the system. Combining a specific engineering case, this work investigates gas–liquid two-phase flow in tunnel sections during filling. We employ a coupled Volume of Fluid (VOF) multiphase model and a Realizable k-ε turbulence model for our simulations. Hydraulic parameters (flow patterns, pressure, velocity) are analyzed using the results. Key findings indicate that higher filling flow rates destabilize the process. Gas retention behavior in low-pressure caverns varies, and gas–liquid eruptions occur at shaft water surfaces. Increased flow rates also intensify phase–pattern transitions, elevate peak pressure and velocity values, and amplify pressure pulsations and velocity fluctuations. Furthermore, faster gas transport in low-pressure caverns triggers flow instability, compromising exhaust efficiency. Full article

Vortex tubes are used in specialized scenarios where conventional refrigeration systems are impractical, such as tool cooling in CNC machines. The internal flow within a vortex tube is highly complex, with numerous factors influencing its energy separation process, and the coefficient of performance for refrigeration is relatively low. To investigate the impact of nozzle type on energy separation performance, vortex tubes with straight-type, converging-type, and converging–diverging-type nozzles were designed. Numerical simulation was conducted to explore their velocity, pressure, and temperature distribution at an inlet pressure of 0.7 MPa and a cold mass fraction of 0.1~0.9. The cooling effect, temperature separation effect, cold outlet mass flow rate, and refrigeration capacity of vortex tubes were assessed. The converging–diverging nozzle increases the gas velocity at the nozzle outlet while it does not significantly enlarge the airflow velocity in the vortex chamber. As the cold mass fraction rises, the cooling performance and cooling capacity of three vortex tubes first increase and then decrease. The maximum cooling effect and cooling capacity of vortex tubes are achieved at cold mass fractions of 0.3 and 0.7, respectively. Under identical conditions, the vortex tube with a converging nozzle achieves the highest cooling effect with a temperature drop of 36.6 K, whereas the vortex tube with converging–diverging nozzles possesses the largest gas flow rate, and the cooling capacity reaches 542.4 W. The vortex tube with straight nozzles exhibits the worst refrigeration performance with a cooling effect of 33.6 K and a cooling capacity of 465.9 W. It is indicated that optimizing the nozzle structure of the vortex tube to reduce flow resistance contributes to enhancing both the gas velocity entering the swirl chamber and the resultant refrigeration performance. Full article

In the presented work, the main challenge of small hydropower plants—converting low river flow velocities into high generator rotations—is investigated. It was established that applying the flow acceleration effect during interaction with surfaces makes it possible to increase the power output of a small hydropower plant by up to 25%, which corresponds to the level of an innovative solution. Stationary flow amplifiers and their influence on the dynamic interaction of blades were studied. It was revealed that the use of the amplification effect in paired configurations contributes to achieving a multiplicative effect. The potential of small hydropower plants was analytically evaluated, taking into account their dimensions and gear systems. The study was carried out using the method of computational fluid dynamics (CFD), which enables the modeling of complex hydrodynamic processes. Based on the developed three-dimensional model of the object and its discretization into a computational mesh, boundary conditions were set, and the finite volume method was applied to solve the Navier–Stokes equations. To account for turbulent flows, the k-epsilon turbulence model was employed. Full article

The cooling medium of the guide bearing heat exchanger in hydro generator sets comes from the upstream dam area, which contains numerous impurities even though it has undergone preliminary treatment. These impurities settle, accumulate, and adhere and form scaling layers in the heat exchanger, seriously affecting its heat transfer performance. This paper presents an innovative investigation of heat exchanger performance under impurity-laden cooling water conditions and proposes an optimization by replacing the conventional round tube structure with a spiral flat tube structure. Numerical simulations are conducted to analyze the flow velocity, pressure, impurity deposition, and temperature distribution of the cooler under actual operating conditions. The results show that the optimized cooler achieves improved velocity uniformity with a lower standard deviation, effectively reducing sediment accumulation. Compared to the prototype, the maximum pressure increases by 55.2% (from 0.562 MPa to 0.872 MPa), which enhances turbulence and improves heat transfer. The sediment volume fraction is significantly reduced by 49% in low-flow operating conditions and 73.7% in high-flow operating conditions. Furthermore, the maximum temperature drops by 5.43 °C, indicating improved thermal performance. These findings confirm the effectiveness of the spiral flat tube design in impurity-rich environments. Full article

Background/Objectives: Oral delivery of biologics offers advantages for patient access and adherence compared to injection, but suffers from low bioavailability due to mucosal barriers and drug degradation in the gastrointestinal tract. We previously developed an oral self-pressurized aerosol (OSPRAE) capsule that uses effervescent excipients to generate CO₂ gas, building internal pressure to eject powdered drug at high velocity across intestinal mucosa. Methods: Here, we developed two key design improvements: (i) an enteric covering to protect the capsule delivery orifice in gastric fluids and (ii) reduced humidity content of capsules to extend shelf-life. Results: Enteric-covered capsules prevented drug release in simulated gastric fluid and then enabled rapid release upon transfer to simulated intestinal fluid. Burst pressure for enteric-covered capsules was ~3–4 times higher than non-covered capsules. After storage for up to three days, the capsules’ effervescent excipients pre-reacted, making them unable to achieve high pressure during subsequent use. To address this limitation, we prepared capsules under reduced humidity conditions, which inhibited pre-reaction of effervescent excipients during storage, and a polyurethane coating to improve water uptake into the capsule to drive the effervescence reaction in intestinal fluid. Conclusions: These design improvements enable improved functionality of OSPRAE capsules for continued translation in pre-clinical and future clinical development. Full article

Addressing the insufficient research on the aerodynamic performance of the coupled last stage and exhaust hood structure in compact marine steam turbines under off-design conditions, this paper establishes for the first time a fully three-dimensional coupled model. It systematically analyzes the influence of the last-stage moving blade shrouds and exhaust hood stiffeners on steam flow loss, static pressure recovery, and vibrational excitation. The research methodology includes the following: employing a hybrid structured-unstructured meshing technique, conducting numerical simulations based on the Shear Stress Transport (SST) turbulence model, and utilizing the static pressure recovery coefficient, total pressure loss coefficient, and cross-sectional flow velocity non-uniformity as performance evaluation metrics. The principal findings are as follows: (1) After installing self-locking shrouds on the moving blades, steam flow loss is reduced by 4.7%, and the outlet pressure non-uniformity decreases by 12.3%. (2) Although the addition of cruciform stiffeners in the diffuser section of the exhaust hood enhances structural rigidity, it results in an 8.4% decrease in the static pressure recovery coefficient, necessitating further optimization of geometric parameters. (3) The coupled model exhibits optimal aerodynamic performance at a 50% design flow rate and 100% design exhaust pressure. The results provide a theoretical basis for the structural optimization of low-noise compact steam turbines. Full article

This study investigates the behavior of glass fiber/polyester layered composites under low-velocity impact conditions, focusing on optimizing layer configurations and fiber types to enhance impact resistance. Composites were fabricated using a combination of E-glass mat and woven glass fibers with orthophthalic polyester resin, employing the hand lay-up method. Impact tests were conducted using a drop hammer device. Key variables included the number of layers and fiber types, with impacts performed using flathead and hemispherical impactors. The results showed that increasing the number of layers significantly enhanced energy absorption and peak contact force. Specifically, five-layer samples exhibited a 351% increase in energy absorption and a 212% increase in peak contact force compared to two-layer samples. Mat fibers outperformed woven fibers, with mat-only samples absorbing 21.8% more energy and showing 5.8% higher peak forces. Additionally, flathead impactors generated 101% higher peak forces and caused more severe damage than hemispherical impactors. Observed failure modes included fiber breakage, matrix cracking, and delamination, all influenced by impact parameters and material characteristics. These findings provide valuable guidance for designing composite materials with improved resistance to impact, with potential applications in the aerospace, marine, and automotive industries. Full article